eh- pon -i- m -us
Let's break it down:
* eh: The "e" sound is short and similar to the "e" in "bed."
* pon: The "pon" sound is pronounced like the word "pon."
* i-m: The "i-m" sounds like the word "him."
* us: The "us" sounds like the word "us."
Here's a helpful tip: Think of the word "eponymous" as "eh-pon-i-m-us."